2 * Copyright (c) 2006,2008,2010 Joseph Koshy
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS `AS IS' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 #include "_libelf_ar.h"
36 ELFTC_VCSID("$Id: libelf_ar.c 3174 2015-03-27 17:13:41Z emaste $");
38 #define LIBELF_NALLOC_SIZE 16
41 * `ar' archive handling.
43 * `ar' archives start with signature `ARMAG'. Each archive member is
44 * preceded by a header containing meta-data for the member. This
45 * header is described in <ar.h> (struct ar_hdr). The header always
46 * starts on an even address. File data is padded with "\n"
47 * characters to keep this invariant.
49 * Special considerations for `ar' archives:
51 * There are two variants of the `ar' archive format: traditional BSD
52 * and SVR4. These differ in the way long file names are treated, and
53 * in the layout of the archive symbol table.
55 * The `ar' header only has space for a 16 character file name.
57 * In the SVR4 format, file names are terminated with a '/', so this
58 * effectively leaves 15 characters for the actual file name. Longer
59 * file names stored in a separate 'string table' and referenced
60 * indirectly from the name field. The string table itself appears as
61 * an archive member with name "// ". An `indirect' file name in an
62 * `ar' header matches the pattern "/[0-9]*". The digits form a
63 * decimal number that corresponds to a byte offset into the string
64 * table where the actual file name of the object starts. Strings in
65 * the string table are padded to start on even addresses.
67 * In the BSD format, file names can be upto 16 characters. File
68 * names shorter than 16 characters are padded to 16 characters using
69 * (ASCII) space characters. File names with embedded spaces and file
70 * names longer than 16 characters are stored immediately after the
71 * archive header and the name field set to a special indirect name
72 * matching the pattern "#1/[0-9]+". The digits form a decimal number
73 * that corresponds to the actual length of the file name following
74 * the archive header. The content of the archive member immediately
75 * follows the file name, and the size field of the archive member
76 * holds the sum of the sizes of the member and of the appended file
79 * Archives may also have a symbol table (see ranlib(1)), mapping
80 * program symbols to object files inside the archive.
82 * In the SVR4 format, a symbol table uses a file name of "/ " in its
83 * archive header. The symbol table is structured as:
84 * - a 4-byte count of entries stored as a binary value, MSB first
85 * - 'n' 4-byte offsets, stored as binary values, MSB first
86 * - 'n' NUL-terminated strings, for ELF symbol names, stored unpadded.
88 * In the BSD format, the symbol table uses a file name of "__.SYMDEF".
89 * It is structured as two parts:
90 * - The first part is an array of "ranlib" structures preceded by
91 * the size of the array in bytes. Each "ranlib" structure
92 * describes one symbol. Each structure contains an offset into
93 * the string table for the symbol name, and a file offset into the
94 * archive for the member defining the symbol.
95 * - The second part is a string table containing NUL-terminated
96 * strings, preceded by the size of the string table in bytes.
98 * If the symbol table and string table are is present in an archive
99 * they must be the very first objects and in that order.
104 * Retrieve an archive header descriptor.
108 _libelf_ar_gethdr(Elf
*e
)
116 if ((parent
= e
->e_parent
) == NULL
) {
117 LIBELF_SET_ERROR(ARGUMENT
, 0);
121 assert((e
->e_flags
& LIBELF_F_AR_HEADER
) == 0);
123 arh
= (struct ar_hdr
*) (uintptr_t) e
->e_hdr
.e_rawhdr
;
125 assert((uintptr_t) arh
>= (uintptr_t) parent
->e_rawfile
+ SARMAG
);
126 assert((uintptr_t) arh
<= (uintptr_t) parent
->e_rawfile
+
127 parent
->e_rawsize
- sizeof(struct ar_hdr
));
129 if ((eh
= malloc(sizeof(Elf_Arhdr
))) == NULL
) {
130 LIBELF_SET_ERROR(RESOURCE
, 0);
134 e
->e_hdr
.e_arhdr
= eh
;
135 e
->e_flags
|= LIBELF_F_AR_HEADER
;
137 eh
->ar_name
= eh
->ar_rawname
= NULL
;
139 if ((eh
->ar_name
= _libelf_ar_get_translated_name(arh
, parent
)) ==
143 if (_libelf_ar_get_number(arh
->ar_uid
, sizeof(arh
->ar_uid
), 10,
146 eh
->ar_uid
= (uid_t
) n
;
148 if (_libelf_ar_get_number(arh
->ar_gid
, sizeof(arh
->ar_gid
), 10,
151 eh
->ar_gid
= (gid_t
) n
;
153 if (_libelf_ar_get_number(arh
->ar_mode
, sizeof(arh
->ar_mode
), 8,
156 eh
->ar_mode
= (mode_t
) n
;
158 if (_libelf_ar_get_number(arh
->ar_size
, sizeof(arh
->ar_size
), 10,
163 * Get the true size of the member if extended naming is being used.
165 if (IS_EXTENDED_BSD_NAME(arh
->ar_name
)) {
166 namelen
= arh
->ar_name
+
167 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE
;
168 if (_libelf_ar_get_number(namelen
, sizeof(arh
->ar_name
) -
169 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE
, 10, &nlen
) == 0)
176 if ((eh
->ar_rawname
= _libelf_ar_get_raw_name(arh
)) == NULL
)
188 free(eh
->ar_rawname
);
192 e
->e_flags
&= ~LIBELF_F_AR_HEADER
;
193 e
->e_hdr
.e_rawhdr
= (unsigned char *) arh
;
199 _libelf_ar_open_member(int fd
, Elf_Cmd c
, Elf
*elf
)
205 char *member
, *namelen
;
207 assert(elf
->e_kind
== ELF_K_AR
);
209 next
= elf
->e_u
.e_ar
.e_next
;
212 * `next' is only set to zero by elf_next() when the last
213 * member of an archive is processed.
215 if (next
== (off_t
) 0)
218 assert((next
& 1) == 0);
220 arh
= (struct ar_hdr
*) (elf
->e_rawfile
+ next
);
223 * Retrieve the size of the member.
225 if (_libelf_ar_get_number(arh
->ar_size
, sizeof(arh
->ar_size
), 10,
227 LIBELF_SET_ERROR(ARCHIVE
, 0);
232 * Adjust the size field for members in BSD archives using
235 if (IS_EXTENDED_BSD_NAME(arh
->ar_name
)) {
236 namelen
= arh
->ar_name
+
237 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE
;
238 if (_libelf_ar_get_number(namelen
, sizeof(arh
->ar_name
) -
239 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE
, 10, &nsz
) == 0) {
240 LIBELF_SET_ERROR(ARCHIVE
, 0);
244 member
= (char *) (arh
+ 1) + nsz
;
247 member
= (char *) (arh
+ 1);
250 if ((e
= elf_memory(member
, sz
)) == NULL
)
255 e
->e_hdr
.e_rawhdr
= (unsigned char *) arh
;
257 elf
->e_u
.e_ar
.e_nchildren
++;
264 * A BSD-style ar(1) symbol table has the following layout:
266 * - A count of bytes used by the following array of 'ranlib'
267 * structures, stored as a 'long'.
268 * - An array of 'ranlib' structures. Each array element is
269 * two 'long's in size.
270 * - A count of bytes used for the following symbol table.
271 * - The symbol table itself.
275 * A helper macro to read in a 'long' value from the archive.
277 * We use memcpy() since the source pointer may be misaligned with
278 * respect to the natural alignment for a C 'long'.
280 #define GET_LONG(P, V)do { \
281 memcpy(&(V), (P), sizeof(long)); \
282 (P) += sizeof(long); \
286 _libelf_ar_process_bsd_symtab(Elf
*e
, size_t *count
)
288 Elf_Arsym
*symtab
, *sym
;
289 unsigned int n
, nentries
;
290 unsigned char *end
, *p
, *p0
, *s
, *s0
;
291 const size_t entrysize
= 2 * sizeof(long);
292 long arraysize
, fileoffset
, stroffset
, strtabsize
;
295 assert(count
!= NULL
);
296 assert(e
->e_u
.e_ar
.e_symtab
== NULL
);
301 * The BSD symbol table always contains the count fields even
302 * if there are no entries in it.
304 if (e
->e_u
.e_ar
.e_rawsymtabsz
< 2 * sizeof(long))
307 p
= p0
= (unsigned char *) e
->e_u
.e_ar
.e_rawsymtab
;
308 end
= p0
+ e
->e_u
.e_ar
.e_rawsymtabsz
;
311 * Retrieve the size of the array of ranlib descriptors and
312 * check it for validity.
314 GET_LONG(p
, arraysize
);
316 if (arraysize
< 0 || p0
+ arraysize
>= end
||
317 ((size_t) arraysize
% entrysize
!= 0))
321 * Check the value of the string table size.
324 GET_LONG(s
, strtabsize
);
326 s0
= s
; /* Start of string table. */
327 if (strtabsize
< 0 || s0
+ strtabsize
> end
)
330 nentries
= (size_t) arraysize
/ entrysize
;
333 * Allocate space for the returned Elf_Arsym array.
335 if ((symtab
= malloc(sizeof(Elf_Arsym
) * (nentries
+ 1))) == NULL
) {
336 LIBELF_SET_ERROR(RESOURCE
, 0);
340 /* Read in symbol table entries. */
341 for (n
= 0, sym
= symtab
; n
< nentries
; n
++, sym
++) {
342 GET_LONG(p
, stroffset
);
343 GET_LONG(p
, fileoffset
);
345 if (stroffset
< 0 || fileoffset
< 0 ||
346 (size_t) fileoffset
>= e
->e_rawsize
)
354 sym
->as_off
= (off_t
) fileoffset
;
355 sym
->as_hash
= elf_hash((char *) s
);
356 sym
->as_name
= (char *) s
;
359 /* Fill up the sentinel entry. */
362 sym
->as_off
= (off_t
) 0;
364 /* Remember the processed symbol table. */
365 e
->e_u
.e_ar
.e_symtab
= symtab
;
367 *count
= e
->e_u
.e_ar
.e_symtabsz
= nentries
+ 1;
374 LIBELF_SET_ERROR(ARCHIVE
, 0);
379 * An SVR4-style ar(1) symbol table has the following layout:
381 * - The first 4 bytes are a binary count of the number of entries in the
382 * symbol table, stored MSB-first.
383 * - Then there are 'n' 4-byte binary offsets, also stored MSB first.
384 * - Following this, there are 'n' null-terminated strings.
387 #define GET_WORD(P, V) do { \
389 (V) = (P)[0]; (V) <<= 8; \
390 (V) += (P)[1]; (V) <<= 8; \
391 (V) += (P)[2]; (V) <<= 8; \
399 _libelf_ar_process_svr4_symtab(Elf
*e
, size_t *count
)
403 Elf_Arsym
*symtab
, *sym
;
404 unsigned char *p
, *s
, *end
;
407 assert(count
!= NULL
);
408 assert(e
->e_u
.e_ar
.e_symtab
== NULL
);
412 if (e
->e_u
.e_ar
.e_rawsymtabsz
< INTSZ
)
415 p
= (unsigned char *) e
->e_u
.e_ar
.e_rawsymtab
;
416 end
= p
+ e
->e_u
.e_ar
.e_rawsymtabsz
;
418 GET_WORD(p
, nentries
);
421 if (nentries
== 0 || p
+ nentries
* INTSZ
>= end
)
424 /* Allocate space for a nentries + a sentinel. */
425 if ((symtab
= malloc(sizeof(Elf_Arsym
) * (nentries
+1))) == NULL
) {
426 LIBELF_SET_ERROR(RESOURCE
, 0);
430 s
= p
+ (nentries
* INTSZ
); /* start of the string table. */
432 for (n
= nentries
, sym
= symtab
; n
> 0; n
--) {
437 if (off
>= e
->e_rawsize
)
440 sym
->as_off
= (off_t
) off
;
441 sym
->as_hash
= elf_hash((char *) s
);
442 sym
->as_name
= (char *) s
;
447 for (; s
< end
&& *s
++ != '\0';) /* skip to next string */
451 /* Fill up the sentinel entry. */
454 sym
->as_off
= (off_t
) 0;
456 *count
= e
->e_u
.e_ar
.e_symtabsz
= nentries
+ 1;
457 e
->e_u
.e_ar
.e_symtab
= symtab
;
464 LIBELF_SET_ERROR(ARCHIVE
, 0);